The invention relates to broadly to a rechopper for chopped crop that includes first and second rollers having axially parallel rotational axes and peripheral surfaces disposed opposite one another, delimiting a comminution gap and provided with truncated-cone shaped sections, the sections having a base surface, a top surface and provided with peripheral surfaces extending at a slant relative to the rotational axis of the respective roller.
As is known, agricultural harvesting machines such as self-propelled forage harvesters are typically equipped with a rechopper when used to harvest corn. In this case, the rechopper also is referred to as a conditioning device or a corn cracker. Such a rechopper is used to further comminute the crop in a targeted manner, the crop previously comminuted by one or more processing assemblies, such as a chopping assembly. In harvesting corn, the purpose thereof is to prepare the crop for use as livestock feed or for biogas production.
To this end, known rechoppers typically comprise two rollers, which are driven in opposite directions, are disposed parallel to one another and are preloaded against one another, between which already chopped crop is directed to pound (corn) kernels contained in the chopped crop. This improves the digestibility of the subsequent feed for livestock and improving the usability of the crop for biogas production.
Very generally speaking, various requirements are placed on rechoppers. First, good processing quality should be ensured. This means that ideally all the kernels contained in the crop are reliably opened up. On the other hand, however, the crop should not be crushed into a pasty mass, but rather should retain a coarse structure and be well-compressible. Moreover, every effort should be made to prevent individual plant components such as husk leaves from passing through the rechopper without being shortened.
Given that the throughput rates of forage harvesters are high and continuously increase, the rechoppers used therein also must achieve increasingly high throughput rates. Therefore, the throughput rate that can be achieved and the drive power required therefor play a large role, and the drive power must be minimized for reasons of energy efficiency.
Document EP 0 525 422 A2, for example, describes a rechopper with two chopper rollers driven in opposite directions, each of which comprises a plurality of adjacently disposed, wedge-shaped sections, the base surface and top surface of which have the same diameter in every case. The sections are disposed on the respective roller in mirror images relative to one another in the axial direction. That is, a section having a peripheral surface rising in the axial direction is adjoined by a section having a peripheral surface falling in the axial direction, and vice versa. The arrangement of the sections on the rollers disposed opposite one another is complementary. The disadvantage of this arrangement is that prepared chopped crop can often cause blockages in the downstream discharge system, which limits the throughput rate.
Document EP 1 101 397 A1 makes known a rechopper having rollers with wedge-shaped sections, the base surface and top surface of which have the same diameter in every case. As viewed in the axial direction, the sections are alternately disposed such that the base surface of one section always bears against the top surface of the adjacent section. The resulting arrangement is shaped somewhat like a Christmas tree. The arrangement of the sections on the rollers disposed opposite one another is complementary in this case as well. A disadvantage of this design is that, due to the acute angles of the sections, highly complex production engineering is required in order to obtain toothing that works together effectively. A further disadvantage is that, due to the large overlap of oppositely disposed sections in the radial direction, a very large cutting gap forms, into which material can be pressed, which results in an increased power requirement for driving the rechopper. In addition, the selected orientation of the arrangement of the sections on the rollers results in an axial force, which additionally loads the bearings of the rechopper.